1 /*
2 * Copyright (c) 2014 The WebRTC project authors. All Rights Reserved.
3 *
4 * Use of this source code is governed by a BSD-style license
5 * that can be found in the LICENSE file in the root of the source
6 * tree. An additional intellectual property rights grant can be found
7 * in the file PATENTS. All contributing project authors may
8 * be found in the AUTHORS file in the root of the source tree.
9 */
10
11 #include "webrtc/common_audio/fir_filter_neon.h"
12
13 #include <arm_neon.h>
14 #include <assert.h>
15 #include <string.h>
16
17 #include "webrtc/system_wrappers/include/aligned_malloc.h"
18
19 namespace webrtc {
20
FIRFilterNEON(const float * coefficients,size_t coefficients_length,size_t max_input_length)21 FIRFilterNEON::FIRFilterNEON(const float* coefficients,
22 size_t coefficients_length,
23 size_t max_input_length)
24 : // Closest higher multiple of four.
25 coefficients_length_((coefficients_length + 3) & ~0x03),
26 state_length_(coefficients_length_ - 1),
27 coefficients_(static_cast<float*>(
28 AlignedMalloc(sizeof(float) * coefficients_length_, 16))),
29 state_(static_cast<float*>(
30 AlignedMalloc(sizeof(float) * (max_input_length + state_length_),
31 16))) {
32 // Add zeros at the end of the coefficients.
33 size_t padding = coefficients_length_ - coefficients_length;
34 memset(coefficients_.get(), 0.f, padding * sizeof(coefficients_[0]));
35 // The coefficients are reversed to compensate for the order in which the
36 // input samples are acquired (most recent last).
37 for (size_t i = 0; i < coefficients_length; ++i) {
38 coefficients_[i + padding] = coefficients[coefficients_length - i - 1];
39 }
40 memset(state_.get(),
41 0.f,
42 (max_input_length + state_length_) * sizeof(state_[0]));
43 }
44
Filter(const float * in,size_t length,float * out)45 void FIRFilterNEON::Filter(const float* in, size_t length, float* out) {
46 assert(length > 0);
47
48 memcpy(&state_[state_length_], in, length * sizeof(*in));
49
50 // Convolves the input signal |in| with the filter kernel |coefficients_|
51 // taking into account the previous state.
52 for (size_t i = 0; i < length; ++i) {
53 float* in_ptr = &state_[i];
54 float* coef_ptr = coefficients_.get();
55
56 float32x4_t m_sum = vmovq_n_f32(0);
57 float32x4_t m_in;
58
59 for (size_t j = 0; j < coefficients_length_; j += 4) {
60 m_in = vld1q_f32(in_ptr + j);
61 m_sum = vmlaq_f32(m_sum, m_in, vld1q_f32(coef_ptr + j));
62 }
63
64 float32x2_t m_half = vadd_f32(vget_high_f32(m_sum), vget_low_f32(m_sum));
65 out[i] = vget_lane_f32(vpadd_f32(m_half, m_half), 0);
66 }
67
68 // Update current state.
69 memmove(state_.get(), &state_[length], state_length_ * sizeof(state_[0]));
70 }
71
72 } // namespace webrtc
73